Optical touch sensor

ABSTRACT

A method for detecting locations of objects in a plane, including emit light beams, one at a time, at locations along a first edge of a detection area, refract each light beam into multiple divergent light beams, direct each of the divergent beams to arrive at a respective pair of focusing lenses mounted along a second edge of the detection area, opposite the first edge, wherein an intensity profile of each divergent beam has maximum intensity along the center of the beam, for each of the focusing lenses, measure an intensity profile of that portion of the divergent beam that enters the focusing lens, for each pair of focusing lenses receiving a single divergent beam, compare the measured intensity profiles for light arriving at each lens, and determine a location of an object that partially blocks at least one of the divergent beams, based on the compares.

PRIORITY REFERENCE TO PROVISIONAL APPLICATION

This application claims priority benefit from U.S. Provisional Pat.Application No. 63/085,838, entitled OPTICAL TOUCH SENSOR, and filed onSep. 30, 2020, by inventor Stefan Holmgren.

FIELD OF THE INVENTION

The field of the present invention is touchscreens, particularly opticaltouchscreens.

BACKGROUND OF THE INVENTION

Reference is made to FIG. 1 , which is a simplified illustration of afirst prior art optical touchscreen, described in U.S. Pat. No.9,471,170, entitled LIGHT-BASED TOUCH SCREEN WITH SHIFT-ALIGNED EMITTERAND RECEIVER LENSES, and assigned to the assignee of the presentinvention. This touchscreen 900 is surrounded by lens arrays 300 - 303.Emitters 100 - 121 are arranged along two adjacent edges of thetouchscreen, and detectors 200 - 223 are arranged along the remainingtwo edges. The emitters along edges of the touchscreen are shift-alignedwith respect to the detectors along the opposite edges of thetouchscreen. Lenses 300 and 301 are configured to spread light from eachemitter to arrive at two opposite detectors, and lenses 302 and 303 areconfigured such that each detector receives light from two oppositeemitters.

FIG. 1 shows horizontal light beams 400 - 407 and vertical light beams408 - 421, each beam originating at a respective emitter and reachingtwo detectors. Each emitter is synchronously activated with itscorresponding detectors by processor 901. Processor 901 also stores thedetector outputs and calculates touch locations based on these outputs.

Reference is made to FIG. 2 which is a simplified illustration of asecond prior art optical touchscreen, described in U.S. Pat. No.9,063,614, entitled OPTICAL TOUCH SCREENS, and assigned to the assigneeof the present invention. This touchscreen 902 is surrounded by lensarrays 304 - 307. Emitters 122 - 174 are arranged along two adjacentedges of the touchscreen, and detectors 224 - 278 are arranged along theremaining two edges. In contrast to lenses 300 and 301 in FIG. 1 ,lenses 305 and 306 are configured to spread light from each emitter toarrive at numerous detectors. Similarly, lenses 304 and 307 areconfigured such that each detector receives light from numerousemitters, e.g., ±8 channels per diode. FIG. 2 illustrates the dense meshof detected light beams 422 - 474. Each emitter is synchronouslyactivated with its corresponding detectors by processor 903. Processor903 also stores the detector outputs and calculates touch locationsbased on these outputs.

The touchscreen system illustrated in FIG. 1 , has relatively narrowlight channels which provide good signal levels for touch detection.Furthermore, each light beam is shaped to provide signal gradientsacross the width of the beam. These signal gradients enable identifyingprecisely where within the beam the blocking object is located bycomparing the amounts of blocked light detected by differentemitter-detector pairs. Thus, this system provides excellent informationfrom each light channel. In addition, this system works well with alarge pitch (denoted p) between components (e.g., p is between 15 mm and18 mm). However, this system is not optimal for suppressing ghosttouches, as the vertical light beams are nearly parallel, as are thehorizontal light beams.

Reference is made to FIG. 3 , which is a simplified illustration of theghost touch problem. Blocked beams (detections) 725 - 728 createambiguity as to which of locations 910 - 913 contain a touch object. Inthis case, the actual objects are located at locations 910 and 911.

The ghost touch problem exists in the touchscreen of FIG. 1 . Incontrast, the touchscreen system illustrated in FIG. 2 provides a rangeof different angles for the horizontal light beams and for the verticallight beams, e.g., ±20°. This enables the system to suppress ghosttouches well. This system works best with slightly more components,e.g., p ≈12.5 mm, making this system more expensive. The wide angle ofthe emitter beams provides lower signal levels for each emitter-detectorpair, and furthermore, each emitter-detector light channel does notfeature the signal gradients across the width of the beam as in thesystem of FIG. 1 , making touch location calculation less exact. Thetouchscreen system of FIG. 2 also features many more light channels andtherefore is more costly in terms of activating all of theemitter-detector channels and storing and processing the detectionsignals.

The following table summarizes the features of the systems illustratedin FIGS. 1 and 2 .

TABLE I Features of touchscreen systems in FIGS. 1 and 2 FIG. 1 FIG. 2good gradients no gradients good signal levels low signal levels fewcomponents intermediate number of components few channels many channelsbad angles for ghost touch suppression excellent angles for ghost touchsuppression

Publication No. US 2012/0188206 A1 (the “‘206 publication“), entitledOPTICAL TOUCH SCREEN WTH TRI-DIRECTIONAL MICRO-LENSES is a publicationof U.S. Pat. Application Serial No. 13/424,472, which is assigned to theassignee of the present invention. The ‘206 publication discusses anoptical touchscreen in which each emitter beam is split into threeseparate beams, particularly with reference to FIGS. 83, 89, 90, 98 and99 in the ‘206 publication. The motivation for the optical touchscreenin which each emitter beam is split into three separate beams,particularly with reference to FIGS. 83, 89, 90, 98 and 99 in the ‘206publication went as follows. More information is needed in order tosolve the ghost touch problem in the optical touchscreen of FIG. 1 ,namely the problem of trying to uniquely identify multiple touches basedon insufficient positional data. The solution proposed in the ‘206publication is to provide more detection channels, i.e., more grids oflight beams. The more different the grids are, the better theinformation content. So, an added grid skewed at 45 degrees to theexisting grid gives the most information without adding many channels.

However, the additional 45-degree grid requires that the detectorphotodiodes (PDs) be placed along all four edges of the screen, andthus, the configuration of FIG. 1 with LEDs on two edges of thetouchscreen and PDs along the opposite edges of the touchscreen cannotbe used. This leads to a configuration of alternating LEDs and PDs alongthe edges of the screen.

Then there is the choice of whether to use half-lenses on two of thefour edges of the screen, or only standard lenses on all sides, namely,should the lenses along opposite edges of the screen be aligned, orshift-aligned as in FIG. 1 . There are advantages to a shift-alignedconfiguration, as discussed inter alia in U.S. Pat. No. 9,471,170.However, a shift-aligned configuration is complicated in view of theadditional 45-degree channels. Thus, an aligned configuration isrequired in consideration of the additional 45-degree channels.

The aligned configuration of lenses on opposite edges of the screenmeans that the LED and PD components on opposite edges of the screen arealigned as well. However, it had to be determined whether each LED isopposite another LED or opposite a PD. Assuming the central beam fromeach LED expands as it crosses the screen and therefore reaches threecomponents along the opposite edge of the screen - if each LED isopposite another LED, then the central beam from one LED reaches twoPDs. However, this causes trouble with bad information in the center,since the middle of this central beam is directed at an LED, not a PD.On the other hand, if each LED is opposite a PD, the channel is straightacross from LED to PD, but the central beam spanning three oppositecomponents arrives at only one PD (and the two LEDs on either side ofthat PD). In this case, there would be no overlap of channels and thepossibilities of using interpolation of several signals (channels) wouldbe severely limited. The benefits of interpolating overlapping channelsis discussed inter alia in U.S. Pat. No. 9,471,170. The configurationaligning each LED opposite a PD and not featuring overlapping channelscan be used for relatively large objects, as is indicated in ‘206publication, paragraph [0332].

The way to provide overlapping channels is discussed in the ‘206publication at paragraph [0333]; namely, interleaving different lightchannels using small facets to get an even distribution on thetri-directional pattern. The many small facets dilute the signal byspreading light in several directions and also by interleavingneighboring beams. Moreover, the system discussed in the ‘206publication at paragraph [0333] is less flexible than the systemdiscussed in U.S. Pat. No. 9,471,170, in terms of pitch width, as the‘206 publication requires an even number of pitches on both sides of thescreen. The signals are shaped by the focal length and the pitch, andalthough there is good information, it cannot be tailored much, and itlooks like FIGS. 94 and 95 in the ‘206 publication.

The present invention addresses the shortcomings of the prior art. Otheradvantages of the present invention will become apparent from thedescription below.

SUMMARY

There is thus provided in accordance with an embodiment of the presentinvention an optical sensor for detecting locations of objects,including a plurality of lenses arranged along two opposite edges of arectangular detection area, a circuit board mounted underneath thelenses, a plurality of light emitters mounted on the circuit board alonga specific one of the two opposite edges of the rectangular detectionarea, each light emitter operable when activated to project light beamsthrough a respective one of the lenses, wherein the lenses areconfigured to split the light beam projected from each light emitterinto a plurality of divergent light beams directed across therectangular detection area to respective pluralities of the lenses thatare arranged along the edge of the rectangular detection area that isopposite the specific edge, wherein a light intensity of each directedbeam is maximized along the center of the directed beam and adistribution of light intensity within each thus directed beam is known,a plurality of light detectors mounted on the circuit board along theedge of the rectangular detection area that is opposite the specificedge, each detector receiving the light beams directed across therectangular detection area through a respective one of the lenses thatare arranged along the edge of the rectangular detection area oppositethat specific edge, and a processor receiving outputs from the lightdetectors, and calculating a location of an object in the rectangulardetection area based on the known distribution of light intensity withineach directed beam, and the received outputs.

According to further features in embodiments of the invention, theplurality of light emitters is shift-aligned with respect to theplurality of light detectors.

According to further features in embodiments of the invention, thelenses are designed such that light beams of different widths aredirected by the lenses across the rectangular detection area.

According to further features in embodiments of the invention, thelenses are designed such that those of the lenses that are arranged nearcorners of the rectangular detection area direct light beams across therectangular detection area that are narrower than the light beamsdirected across the rectangular detection area by the others of saidlenses.

According to further features in embodiments of the invention, those ofthe lenses that are arranged near corners of the rectangular detectionarea are smaller than the others of the lenses.

According to further features in embodiments of the invention, those ofthe lenses that are arranged near corners of the rectangular detectionarea are designed to split the light beams from respective ones of thelight emitters into fewer divergent light beams than the others of thelenses.

According to further features in embodiments of the invention, thelenses spread the pluralities of divergent light beams in fan-likeshapes, each fan having an apex angle, wherein those of the lenses thatare arranged near corners of the rectangular detection area generatefans of light beams having apex angles that are smaller than the apexangles of the fans of light beams generated by the others of the lenses.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood and appreciated fromthe following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a simplified illustration of a first prior art opticaltouchscreen;

FIG. 2 is a simplified illustration of a second prior art opticaltouchscreen;

FIG. 3 is a simplified illustration of ghost touches;

FIG. 4 is a simplified illustration of the principles of calculating atouch location based on optical signals, in the optical touchscreen ofFIG. 1 , according to the present invention;

FIG. 5 is a simplified illustration of light from an emitter being splitinto three optical channels, in accordance with an embodiment of thepresent invention;

FIG. 6 is a simplified illustration of light from an emitter being splitinto two optical channels, in accordance with an embodiment of thepresent invention;

FIG. 7 is a simplified illustration of distinguishing an actual touchfrom a ghost touch, in accordance with embodiments of the presentinvention;

FIG. 8 is a simplified illustration of five different beams that may becreated by a lens, in accordance with embodiments of the presentinvention;

FIGS. 9 - 12 are illustrations of lenses used in an optical sensor, inaccordance with an embodiment of the present invention;

FIG. 13 is a simplified illustration of an optical touchscreen detectionarea, in accordance with an embodiment of the present invention;

FIGS. 14 - 16 are simplified illustrations of partially overlappingcentral light beams in an optical touchscreen, in accordance with anembodiment of the present invention;

FIGS. 17 - 19 are simplified illustrations of partially overlappingleft-leaning light beams in an optical touchscreen, in accordance withan embodiment of the present invention;

FIGS. 20 - 22 are simplified illustrations of partially overlappingright-leaning light beams in an optical touchscreen, in accordance withan embodiment of the present invention;

FIGS. 23 and 24 are simplified illustrations of the number ofoverlapping light beams provided for touch detection in differentportions of a touchscreen that features the beams of FIGS. 14 - 22 , inaccordance with an embodiment of the present invention;

FIGS. 25 - 27 are simplified illustrations of partially overlapping farleft-leaning light beams in an optical touchscreen, in accordance withan embodiment of the present invention;

FIGS. 28 and 29 are simplified illustrations of partially overlappingfar right-leaning light beams in an optical touchscreen, in accordancewith an embodiment of the present invention;

FIGS. 30 and 31 are simplified illustrations of the number ofoverlapping light beams provided for touch detection in differentportions of a touchscreen, featuring the beams of FIGS. 4, 14, 15 and25 - 29 , in accordance with an embodiment of the present invention;

FIG. 32 is a simplified illustration of an optical touchscreen havingdifferent optics for outer and inner beams crossing the screen, inaccordance with an embodiment of the present invention;

FIG. 33A is a map showing different screen sections in an opticaltouchscreen, the sections having different numbers of overlappingdetection channels, in accordance with an embodiment of the presentinvention;

FIG. 33B illustrates the different screen sections of FIG. 33A usingtext and arrows, in accordance with an embodiment of the presentinvention; and

FIG. 34 is a simplified illustration of the number of overlapping lightbeams provided for touch detection in different portions of atouchscreen for a touchscreen whose lenses are configured to split eachemitter beam into two diverging beams, not three, in accordance with anembodiment of the present invention.

In the disclosure and figures, the following numbering scheme is used.Like numbered elements are similar but not necessarily identical.

TABLE II Elements of Figures Type of element Numbering range FIGS. lightemitters 100 - 199 1, 2, 4 - 6, 8, 13 -32, 34 light detectors 200 - 2991, 2, 4 - 6, 13 -32, 34 lenses 300 - 399 1, 2, 4 - 6, 9 - 32, 34 lightbeams 400 - 699 1, 2, 4 - 6, 8, 14, 15, 17 - 23, 25 -30 light detection700 - 799 3 - 6 other items 900 - 999 1 - 5, 7 - 9, 13 -32, 34

DETAILED DESCRIPTION

The following table summarizes certain features of a touchscreenaccording to the present invention, in relation to features of the priorart touchscreens illustrated in FIGS. 1 and 2 .

TABLE III Features of the Present Invention FIG. 1 Present inventionFIG. 2 good gradients good gradients no gradients good signal levelsintermediate signal levels low signal levels few components fewcomponents intermediate number of components few channels intermediateno. channels many channels bad angles for ghost touch suppressionexcellent angles for ghost touch suppression excellent angles for ghosttouch suppression

Reference is made to FIG. 4 , which is a simplified illustration of theprinciples of calculating a touch location based on optical signals, inthe optical touchscreen of FIG. 1 , according to the present invention.FIG. 4 illustrates signal gradients in a touchscreen embodiment. Emitter109 projects vertical light beam 409 across detection area 900, detectedby neighboring detectors 221 and 222. Specifically, beam portion 475 isdetected by detector 222 and beam portion 476 is detected by detector221. Beam portion 475 is shown as a parallelogram that extends from thelens at emitter 109 to the lens at detector 222, and beam portion 476 isshown as a parallelogram that extends from the lens at emitter 109 tothe lens at detector 221; the dashed lines in beam portions 475 and 476indicate the center of each beam portion. Lenses 301 shape beam 409 suchthat maximum intensity is along the center of the beam, and theintensity gradient is reduced toward the edges of the beam, asrepresented by detections 709 and 708. Lenses 303 are similar to lenses301 and collect the incoming light onto the detectors. When an objectblocks part of beam portion 475 from reaching detector 222 and part ofbeam portion 476 from reaching detector 221, the location of the objectalong the width of beam 409 is determined by comparing the detections atdetectors 221 and 222: if the detections are equal, the object is alongthe beam’s central axis, and if the detections are unequal, their ratioindicates how far the object is shifted to one side of the beam’scenter.

FIG. 4 also shows detector 219 receiving light from two emitters 111 and112, specifically, portion 477 of the beam from emitter 111 and portion478 of the beam from emitter 112 arrive at detector 219. As beamportions 477 and 478 overlap, the system determines where along thewidth of the overlap an object is positioned by comparing the detectionsof emitter-detector pair 111-219 with the detections of emitter-detectorpair 112-219.

FIG. 4 shows vertical beams 417 - 419 from emitters 117 - 119 todetectors 211 - 214. Overlapping detected portions 479 of these beamsillustrate that an object placed in detection area 900 will be detectedby at least two emitter-detector pairs, i.e., {(e,d), (e,d+1)} or{(e,d), (e+1,d)}, where e and e+1 are two neighboring emitters and d andd+1 are two neighboring detectors. As explained above, the overlappingdetections and the shaped light beams provide signal gradients thatenable precise calculations of locations of objects touching the screen,or otherwise entering the plane of these light beams, by comparing themagnitude of detections of a single object by several emitter-detectorpairs. One method of comparing these detections is by interpolation. Thesynchronized activation of emitter-detector pairs is controlled byprocessor 903. Processor 903 also stores detector outputs and calculatesa location of a detected object based on those outputs.

FIG. 4 shows that the emitter lenses along two edges of detection area900 are shift-aligned with the detector lenses along the opposite edgesof detection area 900, and the beam from each emitter detected by twoopposite detectors can be expressed as being detected by detectors thatare offset +/-0.5 lens pitch from opposite the emitter. According to thepresent invention, light from each emitter is split into several beamsdetected by additional pairs of detectors to provide additionaldetection channels and more angles for ghost touch suppression.

Thus, in certain embodiments of the invention, a first additional beamis directed towards detectors, along the opposite edge of the detectionarea, that are offset 1.5 and 2.5 lens pitches from opposite theemitter, and a second additional beam is directed towards detectors,along the opposite edge of the detection area, that are offset -1.5 and-2.5 lens pitches from opposite the emitter. These additional beams areillustrated in FIGS. 17 - 22 . When all three sets of beams areprovided, namely, the initial beam directed at the detectors that areoffset +/-0.5 lens pitches from opposite the emitter, plus the twoadditional beams, six sets of detection channels are provided. This isillustrated in FIGS. 23 and 24 .

In other embodiments of the invention, different additional beams areused to provide a wider range of angles for ghost touch suppression;namely, a first additional beam is directed towards neighboringdetectors that are offset 3.5 and 4.5 lens pitches from opposite theemitter, and a second additional beam is directed towards detectors thatare offset -3.5 and -4.5 lens pitches from opposite the emitter. Theseadditional beams are illustrated in FIGS. 25 - 29 . When these beams areprovided together with the initial beam directed at the detectors thatare offset +/-0.5 lens pitches from the emitter, six sets of detectionchannels are provided, as illustrated in FIGS. 30 and 31 . Still otherembodiments of the invention provide additional beams with largeremitter-detector offsets, as illustrated in FIGS. 25 - 29 , but provideadditional beams with smaller emitter-detector offsets near the edges ofthe detection area, as illustrated in FIGS. 32 and 33 .

Reference is made to FIG. 5 , which is a simplified illustration oflight from an emitter being split into three optical channels, inaccordance with an embodiment of the present invention. FIG. 5illustrates splitting each emitter beam into three separate, divergingbeams 484 - 486, each separate beam being shaped with a gradient asdescribed hereinabove with respect to FIG. 4 , such that the highestintensity is along the center of each of separate beam, and the lightintensity is reduced from the center of the beam outward. These split,shaped beams are formed by lenses 309, and similar lenses 311 areprovided at the detectors for directing beams in each of the threedirections onto each detector. Each of beams 484 - 486 arrives at twodetectors. Specifically, beam 484 arrives at detectors 214 and 215; beam485 arrives at detectors 212 and 213; and beam 486 arrives at detectors210 and 211. As such, the minimum angle between beams 484 and 485, andbetween beams 485 and 486, is

$\theta_{\min} = \tan^{- 1}\left( \frac{2\text{p}}{\text{L}} \right)$

where p is the pitch between neighboring components and L is thedistance between the row of emitters and the opposite row of detectors.

Although FIG. 5 shows each beam split into three separate, shaped beams,in other embodiments of the invention each beam is split into only twoseparate, shaped beams, providing a greater amount of light for eachseparate beam.

Reference is made to FIG. 6 illustrating light from emitter 118 beingsplit into two separate beams 484 and 485, each separate beam beingshaped with a gradient as described hereinabove with respect to FIGS. 4and 5 , such that the highest intensity is along the center of eachseparate beam, and the light intensity is reduced from the center of thebeam outward. These split, shaped beams are formed by lenses 309, andsimilar lenses 311 are provided at the detectors for directing beams ineach of the two directions onto the detectors. Each of beams 484 and 485arrives at two detectors. Specifically, beam 484 arrives at detectors213 and 214, and beam 485 arrives at detectors 211 and 212. As such, theminimum angle between beams 484 and 485, is

$\theta_{\min} = \tan^{- 1}\left( \frac{2\text{p}}{\text{L}} \right)$

where p is the pitch between neighboring components and L is thedistance between the row of emitters and the opposite row of detectors.

Beams 484 and 485 are both projected by emitter 118. Lenses 309 splitand shape these two beams and direct them at detectors 211 -214, vialenses 311. The detections at detectors 211 - 214 are indicated bysloping curves 711 - 714. The maximum intensity for each beam is alongits center, indicated by the maximum of each curve 711 - 714 being nearthe beam center and declining outward.

Reference is made to FIG. 7 , which is a simplified illustration ofdistinguishing an actual touch from a ghost touch, in accordance withembodiments of the present invention. FIG. 7 shows two touches indetection area 904 and illustrates that, in a system with two divergingbeams for each emitter as illustrated in FIG. 6 , the locations of thefour candidate touch points indicated by blocked left-sloping beams 484of FIG. 6 are slightly different than the four candidate touch pointsindicated by the blocked right-sloping beams 485 of FIG. 6 . Arrows 931indicate the directions of the right-sloping vertical and horizontalbeams, and arrows 932 indicate the directions of the left-slopingvertical and horizontal beams. The right-sloping beams indicate possibletouch locations 910, 911, 912′ and 913′, and the left-sloping beamsindicate possible touch locations 910, 911, 912″ and 913″. Thus,locations 910 and 911 at which actual objects are present are identicalfor both sets of beams, whereas the ghost locations 912 and 913 are notthe same. Accordingly, by comparing the touch locations indicated by thedifferent sets of beams, it is determined that locations that areidentical for the different sets of beams are actual touch locations,and locations that are not identical for the different sets of beams arenot touch locations. Put differently, by combining the touch detectionsfrom all of the beams, it is determined that locations whose detectionsby different sets of beams are concentrated at specific locations areactual touch locations, and locations for which the combined detectionsfrom different sets of beams are more diffuse are not touch locations.Splitting each emitter beam into three diverging beams provides a morerobust solution to the ghost touch problem. In addition, the larger theangle between the diverging beams as discussed hereinbelow, the morerobust the elimination of ghost touches.

Thus, splitting the light from each emitter into two or three beamsprovides different angled beams that resolve many ghost touch situationsthat the touchscreen of FIG. 1 cannot similarly resolve. In addition,the split beams cover most of the display area with many differentoverlapping beams, providing greater resolution and precision forcalculating touch locations.

Reference is made to FIG. 8 , which is a simplified illustration of fivedifferent beams that may be created by a lens, in accordance withembodiments of the present invention. FIG. 8 shows five different beams487 - 491 that may be created from emitter 118 by a lens. As discussedhereinabove, each of the five beams is shaped to have maximum intensityalong the center with the intensity decreasing further from the centralline. This beam shape enables identifying where within the width of thebeam an object is located based on the amount of light it blocks. Eachbeam is directed toward a pair of detectors at the opposite edge of thedetection area. In certain embodiments of the invention, each lenscreates three of these five beams. In certain embodiments discussedhereinbelow the lenses farther from the corners of detection area 904generate the central beam 489 and the two outer beams 487 and 491, inorder to provide beams separated by large angles, whereas lenses closerto the corners of the detection area are configured to generate thethree inner beams 488 - 490, as an outer beam 487 or 491 would bedirected outside detection area 904 and would not reach a detector onthe opposite edge.

Reference is made to FIGS. 9 - 12 , which are illustrations of lensesused in an optical sensor, in accordance with an embodiment of thepresent invention. FIG. 9 shows a touchscreen having detection area 904surrounded by lens structures 309 - 312, and cross-sections thereof.

FIG. 10 shows lens structure 309 of the touchscreen in FIG. 9 . Thislens structure is mounted above a series of light emitters, and itsplits the light from each emitter into three separate beams. FIG. 10shows focusing lenses 324 and 325, and lenses 327 and 328 that split thelight into separate beams.

FIG. 11 shows one of focusing lenses 325 and the associated portion oflens 327, having a repeating three-facet pattern indicated by threearrows that split the light into three separate beams. In sensorsconfigured with two beams for each emitter instead of three, lens 327has a repeating sawtooth pattern of facets in two directions to createtwo diverging beams.

FIG. 12 shows a section of lens structure 309 near the corner of thetouch detection area. This section includes focusing lens 324 andassociated lens 328 for splitting the light. Because this lens is near acorner of the detection area, lens 328 is configured to direct the lightso that the rightmost beam arrives at a detector on the opposite edge ofthe detection area, and in some embodiments this section splits thelight into fewer beams than the other sections. In certain embodiments,this section of lenses is smaller than the others and is thus configuredto create more concentrated beams of light than the other sectionsbecause an edge of the screen is covered by fewer overlapping beams thanother screen sections.

Reference is made to FIG. 13 , which is a simplified illustration of anoptical touchscreen detection area, in accordance with an embodiment ofthe present invention. FIG. 13 shows a frame of lenses 308 - 311surrounding detection area 904, in accordance with an embodiment of thepresent invention. Each lens in lens array 308 directs beams from arespective one of emitters 100 - 107 across detection area 904. Eachlens in lens array 310 directs incoming light onto a respective one ofdetectors 200 - 208. The number of detectors 200 - 208 is greater thanthe number of opposite emitters 100 - 107, as the emitters and detectorsare shift-aligned. This is evident from lens array 310 which featuresseven full-lenses and two half-lenses at either end of array 310,whereas lens array 308 features eight full lenses. Each lens in lensarray 309 directs light beams from a respective one of emitters 108 -121 across detection area 904. Each lens, or half-lens at either end, inlens array 311 directs incoming light onto a respective one of detectors209 - 223. The number of detectors 209 - 223 is greater than the numberof opposite emitters 108 - 121, as the emitters and detectors areshift-aligned. This is evident from lens array 311 which featuresthirteen full-lenses and two half-lenses at either end of array 311,whereas lens array 309 features fourteen full lenses. As discussedhereinabove with reference to FIGS. 5 and 6 , light from each emitter issplit into multiple separate shaped beams, and each beam arrives at twoneighboring detectors along the opposite edge of detection area 904. Anemitter-detector pair refers to a portion of the light beam from oneemitter that arrives at one opposite detector. The following figuresillustrate these portions to indicate the various emitter-detector pairsproviding detection information in accordance with embodiments of thepresent invention.

Reference is made to FIGS. 14 - 16 , which are simplified illustrationsof partially overlapping central light beams in an optical touchscreen,in accordance with an embodiment of the present invention. FIG. 14 showsa first set of beam portions 500 - 513, namely, the lefthand portion ofthe central beam from each emitter. These beam portions provide a firstset of emitter-detector detection channels.

FIG. 15 shows a second set of beam portions 514 - 527, namely, theright-hand portion of the central beam from each emitter. These beamportions provide a second set of emitter-detector detection channels.

FIG. 16 shows coverage of detection area 904 by beam portions 500 - 527shown in FIGS. 14 and 15 . FIG. 16 indicates that most of detection area904 is covered by two beam portions; i.e., two detection channels,except for two narrow triangular sections at the outer edges ofdetection area 904, which are only covered by one detection channel. Asimilar coverage map exists for the horizontal beams traveling fromemitters 100 - 107 to detectors 200 - 208.

Reference is made to FIGS. 17 - 19 , which are simplified illustrationsof partially overlapping left-leaning light beams in an opticaltouchscreen, in accordance with an embodiment of the present invention.FIG. 17 shows a third set of beam portions 528 - 539, namely, thelefthand portion of the left-leaning beam from each emitter. These beamportions provide a third set of emitter-detector detection channels.

FIG. 18 shows a fourth set of beam portions 540 - 551, namely, theright-hand portion of the left-leaning beam from each emitter. Thesebeam portions provide a fourth set of emitter-detector detectionchannels.

FIG. 19 shows additional coverage of detection area 904 by theleft-leaning beams; i.e., beam portions 528 - 551 shown in FIGS. 17 and18 . FIG. 19 indicates that most of detection area 904 is covered by twobeam portions; i.e., two detection channels, except for a first narrowtriangular section along the outer left edge of left-leaning beam 528,and a wider triangular section at the outer right edge of left-leaningbeam 551, which are only covered by one detection channel. FIG. 19 alsoillustrates two triangular sections at the outer edges of detection area904 that are not covered by these left-leaning beams. A similar coveragemap exists for the horizontal beams traveling from emitters 100 - 107 todetectors 200 - 208. FIG. 19 indicates series 921 of emitters and series920 of detectors that are active in providing the illustrated detectionchannels 528 - 551.

Reference is made to FIGS. 20 - 22 , which are simplified illustrationsof partially overlapping right-leaning light beams in an opticaltouchscreen, in accordance with an embodiment of the present invention.FIG. 20 shows a fifth set of beam portions 563 - 574; namely, thelefthand portion of the right-leaning beam from each emitter. These beamportions provide a fifth set of emitter-detector detection channels.

FIG. 21 shows a sixth set of beam portions 575 - 586, namely, theright-hand portion of the right-leaning beam from each emitter. Thesebeam portions provide a sixth set of emitter-detector detectionchannels.

FIG. 22 shows additional coverage of detection area 904 by theright-leaning beams; i.e., beam portions 563 - 586 shown in FIGS. 20 and21 . FIG. 22 indicates that most of detection area 904 is covered by twobeam portions; i.e., two detection channels, except for a first narrowtriangular section along the outer right edge of right-leaning beam 586,and a wider triangular section at the outer left edge of right-leaningbeam 563, which are only covered by one detection channel. FIG. 22 alsoillustrates two triangular sections at the outer edges of detection area904 that are not covered by these right-leaning beams. A similarcoverage map exists for the horizontal beams traveling from emitters100 - 107 to detectors 200 - 208. FIG. 22 indicates series 923 ofemitters and series 922 of detectors that are active in providing theillustrated detection channels 563 - 586.

Reference is made to FIGS. 23 and 24 , which are simplifiedillustrations of the number of overlapping light beams provided fortouch detection in different portions of a touchscreen that features thebeams of FIGS. 14 - 22 , in accordance with an embodiment of the presentinvention. FIG. 23 shows coverage of detection area 904 when all sixsets of detection channels discussed hereinabove with reference to FIGS.14 - 22 are combined. The central portion of detection area 904 iscovered by multiple detection signals from all six sets of detectionbeams - the central, left-leaning and right-leaning beams. However, FIG.23 indicates areas near the edges of detection area 904 that are coveredby only three or four sets of detection signals, and areas covered byonly one or two detection signals.

FIG. 24 indicates the number of detection channels covering differentportions of detection area 904, in the embodiment illustrated in FIG. 23. The number of detection channels varies between 1 - 6. A similar mapof detection channels applies to the horizontal beams, from emitters100 - 107 to detectors 200 - 208.

Reference is made to FIGS. 25 - 27 , which are simplified illustrationsof partially overlapping far left-leaning light beams in an opticaltouchscreen, in accordance with an embodiment of the present invention.FIG. 25 illustrates detection channels between each emitter and arespective detector that is offset 4.5 lens pitches from opposite theemitter; FIG. 26 illustrates detection channels between each emitter anda respective detector that is offset 3.5 lens pitches from opposite theemitter; and FIG. 27 illustrates the combined area covered by these twodetection channels. FIG. 27 indicates series 925 of emitters and series924 of detectors that are active in providing the illustrated detectionchannels 600 - 619.

Reference is made to FIGS. 28 and 29 , which are simplifiedillustrations of partially overlapping far right-leaning light beams inan optical touchscreen, in accordance with an embodiment of the presentinvention. FIG. 28 illustrates detection channels between each emitterand a respective detector that is offset -3.5 lens pitches from oppositethe emitter; FIG. 29 illustrates detection channels between each emitterand a respective detector that is offset -4.5 lens pitches from oppositethe emitter.

Reference is made to FIGS. 30 and 31 , which are simplifiedillustrations of the number of overlapping light beams provided fortouch detection in different portions of a touchscreen, featuring thebeams of FIGS. 4, 14, 15 and 25 - 29 , in accordance with an embodimentof the present invention. FIGS. 30 and 31 show the number of channelscovering different portions of the detection area that utilize the beamsillustrated in FIGS. 4, 14, 15 and 25 - 29 . FIGS. 30 and 31 show thatthe outer portions of the detection area have fewer detection channelsthan the central portion of the detection area. FIGS. 30 and 31 indicateseries 925, 927 of emitters and series 924, 926 of detectors that areactive in providing the illustrated detection channels 600 - 619.

Reference is made to FIGS. 32 and 33 , which are simplifiedillustrations of optical touchscreens having different optics for outerand inner beams crossing the screen, in accordance with an embodiment ofthe present invention. FIG. 32 shows detection channels provided alongthe outer edges of a detection area by beams similar to beams 484 and486 in FIG. 5 . Adding these beams to the system illustrated in FIGS. 30and 31 , provides the outer edge-related portions of the detection areawith additional detection channels.

FIGS. 33A and 33B are two views of detection channel coverage in thesystem of FIGS. 30 and 31 when the additional beams and channels shownin FIG. 32 are provided along the edges of the detection area. FIG. 33Ais color-coded, and FIG. 33B uses text and arrows to indicate the numberof detection channels for each section of the touchscreen. FIGS. 33A and33B show that portions of the detection area have up to nine detectionchannels. Additional beams with even larger emitter-detector offsets canbe added to the optical sensor by modifying the lenses and theemitter-detector activation sequence, and such systems are also withinthe scope of the present invention.

As discussed hereinabove, splitting light from each emitter intoadditional beams adds precision and enables better discrimination ofghost touches. Reference is made to FIG. 34 , which is a simplifiedillustration of the number of overlapping light beams provided for touchdetection in different portions of a touchscreen for a touchscreen whoselenses are configured to split each emitter beam into two divergingbeams, not three, in accordance with an embodiment of the presentinvention. FIG. 34 shows the number of beams, or detection channels,that cover each part of a touchscreen when light from each emitter issplit into four beams, namely, the two beams 484 and 485 of FIG. 6 andone beam to the left of beam 484 and another beam to the right of beam485.

The edge portions of the touchscreen have fewer beams, or detectionchannels, than the center of the screen. In addition, a smaller portionof light from the emitters near the corners is used for touch detectionas fewer channels can be used along the screen edges. Therefore, incertain embodiments of the invention, the light channels traversing thescreen along the screen edges are shaped to be wider and thereforecontain more signal strength than the channels in the middle of thescreen. This requires that the lenses near the screen corners are longerthan the other lenses, and the light channel is spread across a largersegment of the edge near the corner than the other light channels. Interms of calculating touch locations, each beam is assigned coordinatesbased on its center line and a weighted sum of all of these coordinatesis calculated according to the amount that the signal is blocked. Thus,coordinates are also assigned to the edge beams and they are added tothe weighted average, in the same way as the other beams. As a result ofthe larger lenses and wider beams near edges of the screen, the distancebetween the central line of a beam near an edge of the screen and itsneighboring beam is greater than the distance between the central linesof other neighboring beams.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made to thespecific exemplary embodiments without departing from the broader spiritand scope of the invention. Accordingly, the specification and drawingsare to be regarded in an illustrative rather than a restrictive sense.

What is claimed is: 1-7. (canceled)
 8. An optical sensor detectinglocations of objects, comprising: a circuit board; a plurality of lightemitters mounted on said circuit board, each light emitter operable whenactivated to emit light beams; a plurality of light detectors mounted onsaid circuit board, each light detector operable when activated todetect an intensity profile of a light beam entering the light detector;a plurality of focusing lenses mounted along a first edge of arectangular detection area in relation to said light detectors such thateach focusing lens refracts light beams from the detection area onto arespective one of said light detectors; a plurality of diverging lensesmounted along a second edge of the detection area, the second edge beingopposite the first edge, and in relation to said light emitters suchthat each light emitter, when activated, emits single light beamsthrough a respective one of the diverging lenses, and the diverging lensrefracts each single light beam into multiple divergent light beams,wherein each divergent light beam travels across the detection area in adifferent direction relative to the second edge, and is directed to arespective pair of said focusing lenses, wherein an intensity profile ofeach divergent light beam has maximum intensity along the center of thebeam, whereby the divergent light beams from two neighboring emittersthat travel across the detection area, in the same direction relative tothe second edge, arrive at two respective pairs of said focusing lensesthat share a common focusing lens; and a processor activating said lightemitters and said light detectors, receiving light profile outputs fromsaid light detectors, and calculating a location of an object in therectangular detection area based on comparing received outputs from asingle one of said detectors, that correspond to the divergent lightbeams from two neighboring emitters that traveled across the detectionarea in the same direction relative to the second edge, and that wereboth partially blocked by the object.
 9. The optical sensor of claim 8,wherein said plurality of light emitters is shift-aligned with respectto said plurality of light detectors.
 10. The optical sensor of claim 8,wherein said focusing lenses along the first edge are shift-aligned withrespect to said diverging lenses along the second edge.
 11. The opticalsensor of claim 8, wherein the comparing performed by said processorcomprises interpolating the received light profile outputs.
 12. Theoptical sensor of claim 8, wherein each of said diverging lenses thatrefracts each single light beam into a number of divergent light beamscomprises a repeating pattern of that same number of facets and a singlelens separated from the facets by an air gap.
 13. The optical sensor ofclaim 12, wherein said focusing lenses and said diverging lenses havethe same structure.
 14. The optical sensor of claim 8, wherein, whenmultiple objects are located in the detection area, said processorcalculates candidate locations of the multiple objects based on thecomparing, and identifies ghost locations among the candidate locationsbased on comparing the candidate locations.
 15. The optical sensor ofclaim 8, wherein said processor initially calculates multiple candidatelocations of the object in the detection area based on the comparing,and subsequently calculates the location of the object based oncomparing the candidate locations.
 16. An optical method for detectinglocations of objects in a plane, comprising: emit single light beams,one beam at a time, at a plurality of locations along a first edge of adetection area; refract each single emitted light beam into multipledivergent light beams; direct each of the divergent light beams acrossthe detection area to arrive at a respective pair of focusing lensesmounted along a second edge of the detection area, opposite the firstedge, wherein an intensity profile of each divergent light beam hasmaximum intensity along the center of the beam; for each of the focusinglenses, measure an intensity profile of that portion of the divergentlight beam that enters the focusing lens; for each pair of focusinglenses receiving a single divergent light beam, compare the measuredintensity profiles for light arriving at each lens; and determine alocation of an object in the detection area that partially blocks atleast one of the divergent light beams, based on said compares.
 17. Theoptical method of claim 16, wherein each of said focusing lensescomprises a repeating pattern of facets and a single lens separated fromthe facets by an air gap.
 18. The optical method of claim 17, whereinsaid refract is performed by a diverging lens that has the samestructure as said focusing lenses.
 19. The optical method of claim 16,wherein said compare comprises interpolation of the measured intensityprofiles.
 20. The optical method of claim 16, further comprising:identify candidate locations of multiple objects in the detection areathat partially block at least one of the divergent light beams, based onsaid compares; and determine ghost locations among the candidatelocations based on comparing the candidate locations.
 21. The opticalmethod of claim 16, further comprising: identify candidate locations ofthe object, based on said compares; and determine the location of theobject based on comparing the candidate locations.
 22. An optical methodfor detecting locations of objects in a plane, comprising: emit singlelight beams, one beam at a time, at a plurality of locations along afirst edge of a detection area; refract each single emitted light beaminto multiple divergent light beams; direct each of said divergent lightbeams across the detection area in a different direction, relative tothe first edge, to arrive at a respective pair of focusing lensesmounted along a second edge of the detection area, opposite the firstedge, wherein an intensity profile of each divergent light beam hasmaximum intensity along the center of the beam, whereby pairs of thedivergent light beams, emitted at neighboring locations along the firstedge, that travel across the detection area in the same directionrelative to the first edge, arrive at two respective pairs of focusinglenses that share a common focusing lens; measure an intensity profileof the light that enters each focusing lens; for each of the pairs ofdivergent light beams, compare the measured intensity profiles of thelight from each of the divergent light beams in the pair, that entersthe common focusing lens for that pair; and determine a location of anobject in the detection area that partially blocks at least one of thepairs of divergent light beams, based on said compares.
 23. The opticalmethod of claim 22, wherein each of said focusing lenses comprises arepeating pattern of facets and a single lens separated from the facetsby an air gap.
 24. The optical method of claim 23, wherein said refractis performed by diverging lenses that have the same structure as thefocusing lenses.
 25. The optical method of claim 22, wherein saidcompare comprises interpolation of the measured intensity profiles. 26.The optical method of claim 22, further comprising: identify candidatelocations of multiple objects in the detection area that partially blockat least one of the divergent light beams, based on said compares; anddetermine ghost locations among the candidate locations based comparingthe candidate locations.
 27. The optical method of claim 22, furthercomprising: identify candidate locations of the object, based on saidcompares; and determine the location of the object based on comparingthe candidate locations.